SYNAPTIC INTEGRATION AND DEVELOPMENT IN COMMAND NEURONS

本研究将探讨突触的形成机制。 外侧巨细胞(LG)中的整合指令神经元触发 发育中的小龙虾和成年小龙虾的逃生尾部翻转。二 问题将会得到解答。第一个问题是LG如何回应 对机械感觉输入的反应取决于紧张感和 机械感觉中间神经元(MSI)对触觉刺激的时相性 LG上个体MSI的突触联系模式， LG的形态，以及被动膜和主动膜 LG的性质。这个问题将通过录制 两个已确认的MSI，一个时相和一个主音，对 机械感觉刺激，通过识别可能的 LG上的MSI联系站点并记录LG对这些站点的回复 单独和以不同的模式。结构、生物物理 和突触反应数据将被用来重建 LG在定量模型中的综合性质将 细胞对正常输入模式的反应。 第二个问题是LG的综合性能如何 在动物从出生后的鱼苗到成年的生长过程中的变化， 这些变化以及伴随而来的突触变化 LG的输入可以解释尾部翻转行为的变化。我们会 分析LG在2 cm、6 cm和12 cm的综合性能 动物以上述方式，并发展出数量 它们的模型来确定细胞中与生长相关的变化 形状、膜特性和突触输入应该会影响LG。 我们还将确定数字和 LG从已识别的MSI和从 一套机械感觉传入。这项研究应该确定 代偿机制，允许不稳定的双突触 LG在成长过程中保持生存的途径，而非 不稳定的单突触通路失效。因为神经元生长发生在 在所有神经系统中，综合特性的变化 在我们观察到的成长过程中， 补偿这些变化可能会被证明是常见的特征 神经系统的发育。

This research will investigate the mechanisms of synaptic integration in the lateral giant (LG) command neurons that trigger the escape tailflip of both developing and adult crayfish. Two questions will be addressed. The first asks how the LG's responses to mechanosensory inputs depend on the responses of tonic and phasic mechanosensory interneurons (MSIs) to tactile stimuli, the pattern of synaptic contact of individual MSIs on LG, the morphology of LG, and the passive and active membrane properties of LG. This question will be addressed by recording the responses of two identified MSIs, one phasic and one tonic, to mechanosensory stimuli that excite LG, by identifying possible MSI contact sites on LG and by recording LG's responses to them individually and in various patterns. The structural, biophysical and synaptic response data will be used to reconstruct the integrative properties of LG in a quantitative model that will acconut for the cell's responses to its normal patterns of input. The second question asks how the integrative properties of LG change during the animal's growth from post-natal fry to adult, and whether those changes and accompanying changes in synaptic inputs to LG can account for changes in tailflip behavior. We will analyse LG integrative properties in 2 cm, 6 cm and 12 cm animals in the manner described above, and develop quantitative models of them to determine how growth - related changes in cell shape, membrane properties and synaptic inputs should affect LG. We will also determine what changes occur in the number and pattern of inputs LG receives from identified MSIs and from the set of mechanosensory afferents. This study should identify the compensatory mechanisms that allow the labile disynaptic pathway to LG to remain viable during growth while the non- labile monosynaptic pathway fails. Since neuronal growth occurs in all nervous systems, both the changes in integrative properties during growth that we observe and the mechanisms that compensate for those changes may prove to be common features of developing nervous systems.